Biomedical subjects

Makoto Naruse

Publications and source records attributed to Makoto Naruse.

6 recordsLinked to original sources

PubMed2006

Prooxidant action of rhodizonic acid: transition metal-dependent generation of reactive oxygen species causing the formation of 8-hydroxy-2'-deoxyguanosine formation in DNA.

Rhodizonic acid, a six-membered cyclic hydroxyquinone, produced reactive oxygen species as a complex with transition metals. Addition of rhodizonic acid with ferrous ion caused an inactivation of aconitase the most sensitive enzyme to oxidative stress in permeabilized yeast cells. The iron-dependent inactivation of aconitase implies the rhodizonic acid/iron-mediated generation of reactive oxygen species. Spectrophotometric analysis of the interaction of rhodizonic acid with FeSO4 showed that addition of superoxide dismutase could inhibit the oxidation of rhodizonic acid, suggesting that reactive oxygen species produced from rhodizonic acid is superoxide radical. Rhodizonic acid further acted as a prooxidant causing a copper-dependent DNA damage. Treatment of DNA from plasmid pBR322 and calf thymus with rhodizonic acid plus copper caused strand scission and the formation of 8-hydroxy-2'-deoxyguanosine in DNA. Addition of catalase protected DNA from the rhodizonic acid-mediated strand scission, indicating that hydroxyl radical may participate in the DNA damage. Rhodizonic acid also showed a potent copper-reducing activity. These results indicate that copper ion reduced by rhodizonic acid may participate in the formation of superoxide radical that converts to hydrogen peroxide and hydroxyl radical. Other cyclic hydroxyquinones such as four-membered squaric acid and five-membered croconic acid did not show any prooxidant and reducing effects. Cytotoxic effects of tetrahydroquinone the precursor of rhodizonic acid may be related to the prooxidant properties of rhodizonic acid formed in cells.

Copper↗

PubMed2005

Maltol/iron-mediated apoptosis in HL60 cells: participation of reactive oxygen species.

Apoptosis of HL60 cells by maltol was analyzed in relation to the maltol/iron-mediated generation of reactive oxygen species. Addition of maltol with FeSO(4) induced an apoptotic cell death as judged by flow cytometry analysis and DNA fragmentation on electrophoresis, but maltol or iron alone did not affect the cells. Treatment of HL60 cells with maltol/iron complex caused an effective inactivation of aconitase the most sensitive enzyme to reactive oxygen species. Maltol/iron-mediated apoptosis and the inactivation of aconitase was prevented by TEMPOL, the scavenger of reactive oxygen species. These findings suggest that maltol/iron complex can generate reactive oxygen species by the redox cycling, resulting in an apoptosis of HL60 cells. Cytotoxicity of maltol can be explained by the prooxidant properties of this compound.

Aconitate Hydratase↗

PubMed2005

Nanometric summation architecture based on optical near-field interaction between quantum dots.

A nanoscale data summation architecture is proposed and experimentally demonstrated based on the optical near-field interaction between quantum dots. Based on local electromagnetic interactions between a few nanometric elements via optical near fields, we can combine multiple excitations at a certain quantum dot, which allows construction of a summation architecture. Summation plays a key role for content-addressable memory, which is one of the most important functions in optical networks.

Journal Article↗

PubMed2004

Terabit all-optical logic based on ultrafast two-dimensional transmission gating.

Terabit all-optical complementary logic is proposed using two successive time slots to represent a unique logical status. An organic molecular thin film is used as an array of optically controlled optical switches. By utilizing the planar structure of the film and its ultrafast optical response, proof-of-principle fully optical NOT and AND logic operations were demonstrated with 400-fs interval pulses.

Journal Article↗

PubMed2004

Prooxidant activity of curcumin: copper-dependent formation of 8-hydroxy-2'-deoxyguanosine in DNA and induction of apoptotic cell death.

Curcumin, a well-known antioxidant in a principal ingredient of turmeric, acted as a prooxidant causing a copper-dependent DNA damage and the induction of apoptosis. Treatment of DNA from plasmid pBR322 and calf thymus with curcumin plus copper ion caused strand scission and the formation of 8-hydroxy-2(')-deoxyguanosine in DNA. Addition of catalase protected DNA from the curcumin-dependent injuries, indicating that hydroxyl radical may participate in the DNA damage. Flow cytometry analysis showed that curcumin caused an apoptotic cell death of HL60 cells in a dose- and time-dependent manner. Curcumin-mediated apoptosis was closely related to the increase in intracellular reactive oxygen species. On the contrary, capsaicinoids, which have a ortho-methoxy phenolic structure without beta-diketone in the side chain, did not produce 8-hydroxy-2(')-deoxyguanosine. Capsaicin further did not induce apoptosis of HL60 cells, but rather protected cells from prooxidant-induced apoptosis. Curcumin can generate reactive oxygen species as a prooxidant in the presence of transition metals in cells, resulting in DNA injuries and apoptotic cell death. The prooxidant action of curcumin may be related to the conjugated beta-diketone structure of this compound.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2002

Simple integration technique to realize parallel optical interconnects: implementation of a pluggable two-dimensional optical data link.

An assembly technique is presented to realize pluggable or fully integrated optoelectronic systems based on image relays. A method to visually align and assemble optoelectronic chips or fiber bundles to half of a relay is explained. To validate this technique, two-dimensional arrays of vertical-cavity surface-emitting lasers and photodetectors and a fiber image guide have been integrated to gradient index lenses with simple optomechanical parts. Although the connection of these modules was realized with +/-0.5 mm lateral tolerances, parallel optical interconnects were successfully achieved at 10 MHz. The lateral misalignment between chips was on average 20 microm and at worst 60 microm.

Journal Article↗